DotStim

class psychopy.visual.DotStim(win, units='', nDots=1, coherence=0.5, fieldPos=(0.0, 0.0), fieldSize=(1.0, 1.0), fieldShape='sqr', dotSize=2.0, dotLife=3, dir=0.0, speed=0.5, rgb=None, color=(1.0, 1.0, 1.0), colorSpace='rgb', opacity=1.0, contrast=1.0, depth=0, element=None, signalDots='same', noiseDots='direction', name=None, autoLog=None)

This stimulus class defines a field of dots with an update rule that determines how they change on every call to the .draw() method.

This single class can be used to generate a wide variety of dot motion types. For a review of possible types and their pros and cons see Scase, Braddick & Raymond (1996). All six possible motions they describe can be generated with appropriate choices of the signalDots (which determines whether signal dots are the ‘same’ or ‘different’ on each frame), noiseDots (which determines the locations of the noise dots on each frame) and the dotLife (which determines for how many frames the dot will continue before being regenerated).

The default settings (as of v1.70.00) is for the noise dots to have identical velocity but random direction and signal dots remain the ‘same’ (once a signal dot, always a signal dot).

For further detail about the different configurations see Dots (RDK) Component in the Builder Components section of the documentation.

If further customisation is required, then the DotStim should be subclassed and its _update_dotsXY and _newDotsXY methods overridden.

Parameters:

fieldSize

: (x,y) or [x,y] or single value (applied to both

dimensions). Sizes can be negative and can extend beyond the window.

mro() → list

return a type’s method resolution order